A WiMedia compliant CMOS RF power amplifier (PA) for ultra-wideband (UWB) transmitter in the 3.1 to 4.8 GHz band is presented in this paper. The proposed two-stage PA employs a cascode topology on the first stage as driver while the second stage is a simple common source (CS) amplifier. In order to improve the efficiency and output power, the output impedance of the driver amplifier (first stage) is optimized so that it falls on the source-pull contours of the second stage amplifier. On-wafer measurement on the fabricated prototype showed a maximum power gain of +15.8 dB, 0.6 dB gain flatness, +11.3 dBm of output 1 dB gain compression and up to a maximum of 17.3% power added efficiency (PAE) at 4 GHz using a 50 Ω load termination, while consuming only 25.7 mW from a 1.8 V supply voltage. Measurement results obtained are used to create a non-linear powerdependent S-parameter (P2D) model for wideband input and output matching optimizations and co-simulations with the UWB modulated test signals. Using the created P2D model, the PA achieved a maximum output channel power of +3.48 dBm with an error vector magnitude (EVM) of −23.1 dB and complied with the WiMedia mask specifications.
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